This project is a consortium between scientists at Yale University School of Medicine and Harvard Medical School. The objective of the project is to study the biology of human pathogenic Leishmania in their phlebotomine sandfly vectors. The project will involve the disciplines of parasitology, medical entomology, genetics, biochemistry and immunology. Laboratory reared sandflies will be experimentally infected with a number of different Leishmania types and the following aspects of the parasites' biology in the insects will be studied: nutritive requirements of promastigotes in vivo, their complete life cycle, their effect on the vector, differences in sandfly infectivity among various parasite strains, genetic basis of vector competence in sandflies, identification of stage and species specific antigens present on promastigotes in vivo, development of an ELISA technique for assaying Leishmania infection in sandflies, and investigation of the possibility that genetic recombination can occur among related Leishmania types in the insect vector.